Method of increasing the production of deep wells



IE O? Aug. 7, H EN METHOD OF INCREASING THE PRODUCTION OF DEEP WELLS' Filed, Feb. 20, 1933 Patented Aug. 7, 1934 UNITED STATES 1,969,230 PATENT OFFICE METHOD OF INCREASING THE PRODUCTION OF DEEP WELLS Herbert L. McMillen, Tulsa, Okla., assignor to The Independent-Eastern Torpedo Company, Findley, Ohio, a corporation of Ohio Application February 20, 1933, Serial No. 657,510

2 Claims. (Cl. 16621) This invention relates to a method for increasing the production of deep wells, such as oil or gas Wells, in which the producing strata consist of limestone or similar formation that may be dissolved or partially dissolved by a suitable reagent.

Decrease or failure in production from such wells is often caused by the clogging of the pores in the rock by wax or other deposits, and restoration of the production is dependent upon the opening up of the pores by further drilling, or by shooting or by chemical treatment.

The object of the present invention is the provision of an improved method of treating wells, in which production has failed or declined, with special reference to the introduction of a chemical reagent into the bottom of the well and the forcing of the same into the surrounding strata, where it may dissolve the rock to a considerable extent, so that the oil or gas will continue to drain from said strata into the bottom of the well.

This improved method of treatment will be more fully explained in connection with the accompanying drawing, which represents a central vertical section of an oil well.

As represented in the drawing, the well is provided with a casing 1, having a casing head 2 at its upper end, from which the tubing 3 is supported by the tubing ring 4 so that it extends downwardly into the bottom of the well, where a cavity 5 is formed in the oil bearing strata 6. A pipe '7, connected. with the casing head 2, is provided with a valve 8, and a pipe 9, connected with the tubing 3, is similarly provided with a valve 10.

In treating the Well according to my method, the tubing 3 is filled with oil and the valve 10 closed.

The lower part of the casing 1, outside of the tubing 3, is then filled with oil, through the casing head to about one-third of the depth of the well.

Then a chemical reagent, preferably hydrochloric acid of twelve percent to eighteen percent strength, is injected into the casing through the pipe '7. The amount of acid required depends upon the thickness of the oil bearing limestone formation. In practice, the amount used is usually between 500 and 1500 gallons. This acid, being of greater specific gravity than the oil, settles to the bottom of the well.

On top of the acid, sufficient oil is added to fill the casing, or until sufficient pressure is developed to force the acid out from the bottom of the well into the surrounding oil bearing formation, with which it reacts, so that the clogged pores are reopened, permitting oil again to drain into the well.

After the final charge of oil is introduced into the casing, the valve 8 is closed, thereby completing the closure of all outlets from the well. The well is allowed to remain thus closed for 36 to 48 hours, or a sufiicient length of time to allow the acid to complete its reaction with the oil bearing limestone formation.

As the acid eats its way into the limestone formation, a vacuum is formed at the top of the casing. At the end of this period of 36 to 48 hours, the well is opened to relieve the vacuum and is then put to pumping.

By the use of this method of introducing the acid into the well, it has been found that no inhibiting agent is necessary to prevent the acid from attacking the casing or the tubing.

While I have described the invention as particularly adapted for treatment of an oil or gas well, it is apparent that it may be used in any deep well having a producing formation which may be dissolved or partially dissolved by a chemical reagent. It is also to be understood that the invention includes all such modifications as may fall within the scope of the appended claims.

What I claim is:-

1. The method of treating deep wells, which consists in first filling the tubing with oil and closing the upper end thereof, ,then filling the lower part of the casing outside of the tubing with oil, then introducinginto the casing a' suit able. quantity of a chemical reagent which is ofgreater specific gravity than the oil and which is capable. oi Reaction withftheproducing' formaclosing the top of the casing 'until'the reageiit has completed its reac tion with tlie' producing formation. l

2. The method of treating deep wells, which consists in first filling the tubing with oil and closing the upper end thereof, introducing into the casing suitable quantities of oil and a chemical reagent of greater specific gravity than the oil and capable of reaction with the producing formation, until sufiicient pressure is developed to force the reagent into ,the producing formation, at least a part of said oil being introduced into the casing ahead of the reagent, and then closing the top of the casing until the reagent has completed its reaction with the producing formation.

HERBERT L. McMILLEN. 

